1: 3/8 12 1/2

9/20 36 2/3

2/5 1/6 1/ 100

2: 5/ 12+2/3×3/4 3÷(5/7-3/ 14) (28+2/7×7/8)× 1/4

=5/ 12+ 1/2 =3÷( 10/ 14-3/ 14) =(28+ 1/4)× 1/4

=5/ 12+6/ 12 =3÷ 1/2 =28× 1/4+ 1/4× 1/4

= 1 1/ 12 =6 =7+0/ 16.

3: (3/5+ 1/3)× 15 7/ 13×4/5+6/ 13÷5/4

=3/5× 15+ 1/3× 15 = 7/ 13×4/5+6/ 13×4/5

=9+5 =4/5×(7/ 13+6/ 13)

= 14 =4/5× 1

=4/5

(7/24-3/ 16)÷ 1/8 9/5-(2/5÷ 1/2+3/7)

= (7/24-3/ 16)×8 = 9/5-(2/5×2+3/7)

=7/24×8-3/ 16×8 =9/5-(4/5+3/7)

=7/3-3/2 =9/5-4/5-3/7

=5/6 =4/7

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4: 15×4/5÷3

= 15×4/5× 1/3

=4

5: 3/4× 1/6×400

=50

6: 3/ 10÷3/20

=3/ 10×20/3

=2

2-3/ 10= 17/ 10

7: 3/2× 1/2=3/4

3/4+3/2

=3/4+6/4

=9/4